Even the next-generation Java Plug-In can not write to the Program Files directory on Vista. Doing so requires administrator privileges. In order to do this you will need to write a signed applet with both custom native code and a separate native executable. Your native code will need to use ShellExecuteEx and the runas verb in order to elevate your executable to administrative privileges. You can not use Java directly to write to the Program Files directory (unless your native code executes the Java launcher with administrative privileges, and you figure out some other way of getting your class files on to the local disk).

This is the limitation of old Java Plugin, Java Kernel won't help on this issue.

In order to workaround this problem, you need to enable the new generation of Java Plugin by turning on it through Java control panel, under Advanced tab->Java plug-in. We may enabled this by default when we have 6uN FCS.